In traditional laundry operations, a conventional detergent containing nonionic and anionic surfactants is used for cleaning the laundry. Cationic surfactants have been used to achieve improved fabric softness. Since cationic and anionic surfactants are inactivated in a wash bath due to the formation of an insoluble compound, a fabric softener must be added separately in the rinse cycle. Softener agents contain fabric softener additives that are not inactivated by the other ingredients of the detergent and therefore can be part of the formulation of the detergent.
The most conventional fabric softener detergent additives are swellable, natural smectic layered silicates such as montmorillonite and hectorite. The use of such layered silicates in detergents has already been described, for example, in British Patent GB A 2,121,843. Such a detergent additive contains agglomerates of finely divided bentonite with a particle size of less than 74 .mu.m that are agglomerated to form particles approximately 150 to 2000 .mu.m in size which may have a moisture content of 8 to 13%. The agglomerates contain approximately 1 to 5 wt % of a binder in the form of a water glass solution. The detergents produced using such detergent additives contain an anionic surfactant or a nonionic surfactant or a mixture of these surfactants, plus a builder or a builder mixture based on phosphates, preferably polyphosphates, or nitrilotriacetates and carbonates, such as sodium carbonate or sodium bicarbonate. In addition, zeolites such as zeolite A may also be used as the builders. However, the zeolites are not bound to the bentonite aggregates but instead are added only during the process of formulating the detergent.
European Patent Application EP A 385,748 also discloses detergent additives for detergents containing fabric softeners based on agglomerates of a smectic layered silicate such as bentonite enclosed in a finely divided white pigment in order to increase the whiteness. The agglomerates contain additives of nonionic surfactants that are supposed to increase the adhesion of the finely divided white pigment to the agglomerates.
Detergents produced using such detergent additives may contain the same ingredients as the detergents produced according to British Patent GB A 2,121,843. They also include zeolites, but these zeolites are not bound to the bentonite agglomerates. Thus, hard water is not softened before penetrating into the bentonite agglomerates.
European Patent Application EP-A 26,529 discloses detergent formulations that contain quaternary ammonium compounds and tertiary amines in addition to the usual surfactants. Some of these detergent formulations contain zeolites, but even if the latter are present, they are not used to coat agglomerated bentonite.
European Patent Application EP 164,797 discloses fabric softener agglomerates based on smectic layered silicates that are coated with dispersants such as quaternary ammonium salts. This composition is supposed to prevent blockage of automatic washing machines.
U.S. Pat. No. 4,339,335 discloses a detergent formulation that contains, in addition to the usual ingredients, zeolite particles that are attached to the surface of builder particles (sodium carbonate, etc.) with the help of nonionic surfactants. These are essentially granules consisting of sodium carbonate, nonionic surfactants, a coating of zeolite and optionally quaternary ammonium compounds.
German Patent Application DE-A 3,943,019 discloses a granular detergent additive that contains 20 to 45 wt % of a layered silicate such as bentonite, 15 to 20 wt % finely crystalline synthetic zeolite, 0 to 5 wt % water-soluble alkali salts from the class of sulfates, carbonates and phosphates, 0 to 7 wt % polymer acrylic acid salts and 0 to 20 wt % nonionic surfactants. These ingredients are used to prepare an aqueous batch that is then spray dried. No coating of dry bentonite granules with zeolite is disclosed.
German Patent Application DE-A 3,942,066 discloses the production of a granular detergent additive that contains 30 to 90 wt % of a layered silicate, 1 to 40 wt % finely crystalline synthetic zeolite and 0 to 30 wt % water-soluble alkali salts from the class of sulfates, carbonates and silicates, where the zeolite is homogeneously distributed in the granules and is not at the surface of the bentonite granules.
German Patent Application DE-A 3,833,648 discloses a process for producing particulate detergents or detergent additives, whereby swellable clays in particulate form are injected into the spray cone of an aqueous slurry of detergent ingredients and the mixture is dried by hot gases. Again, the zeolite used in this process is not on the surface of clay agglomerates.